/*
 *	API compat layer
 *	written by Jan Engelhardt <jengelh [at] medozas de>, 2008
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License, either
 *	version 2 of the License, or any later version.
 */
#include <linux/ip.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/version.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_arp.h>
#include <net/ip.h>
#include <net/route.h>
#include "compat_skbuff.h"
#include "compat_xtnu.h"

#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 22)
static int xtnu_match_run(const struct sk_buff *skb,
			  const struct net_device *in,
			  const struct net_device *out,
			  const struct xt_match *cm, const void *matchinfo,
			  int offset, unsigned int protoff, int *hotdrop)
#elif LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 27)
static bool xtnu_match_run(const struct sk_buff *skb,
			   const struct net_device *in,
			   const struct net_device *out,
			   const struct xt_match *cm,
			   const void *matchinfo, int offset,
			   unsigned int protoff, bool * hotdrop)
#endif
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 27)
{
    struct xtnu_match *nm = xtcompat_numatch(cm);
    bool lo_drop = false, lo_ret;
    struct xt_match_param local_par = {
	.in = in,
	.out = out,
	.match = cm,
	.matchinfo = matchinfo,
	.fragoff = offset,
	.thoff = protoff,
	.hotdrop = &lo_drop,
	.family = NFPROTO_UNSPEC,	/* don't have that info */
    };

    if (nm == NULL || nm->match == NULL)
	return false;
    lo_ret = nm->match(skb, &local_par);
    *hotdrop = lo_drop;
    return lo_ret;
}
#endif

#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 18)
static int xtnu_match_check(const char *table, const void *entry,
			    const struct xt_match *cm, void *matchinfo,
			    unsigned int matchinfosize,
			    unsigned int hook_mask)
#elif LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 22)
static int xtnu_match_check(const char *table, const void *entry,
			    const struct xt_match *cm, void *matchinfo,
			    unsigned int hook_mask)
#elif LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 27)
static bool xtnu_match_check(const char *table, const void *entry,
			     const struct xt_match *cm, void *matchinfo,
			     unsigned int hook_mask)
#endif
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 27)
{
    struct xtnu_match *nm = xtcompat_numatch(cm);
    struct xt_mtchk_param local_par = {
	.table = table,
	.entryinfo = entry,
	.match = cm,
	.matchinfo = matchinfo,
	.hook_mask = hook_mask,
	.family = NFPROTO_UNSPEC,
    };

    if (nm == NULL)
	return false;
    if (nm->checkentry == NULL)
	return true;
    return nm->checkentry(&local_par);
}
#endif

#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 18)
static void xtnu_match_destroy(const struct xt_match *cm, void *matchinfo,
			       unsigned int matchinfosize)
#elif LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 27)
static void xtnu_match_destroy(const struct xt_match *cm, void *matchinfo)
#endif
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 27)
{
    struct xtnu_match *nm = xtcompat_numatch(cm);
    struct xt_mtdtor_param local_par = {
	.match = cm,
	.matchinfo = matchinfo,
	.family = NFPROTO_UNSPEC,
    };

    if (nm != NULL && nm->destroy != NULL)
	nm->destroy(&local_par);
}
#endif

#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 27)
int xtnu_register_match(struct xtnu_match *nt)
{
    struct xt_match *ct;
    char *tmp;
    int ret;

    ct = kzalloc(sizeof(struct xt_match), GFP_KERNEL);
    if (ct == NULL)
	return -ENOMEM;

    tmp = (char *) ct->name;
    memcpy(tmp, nt->name, sizeof(nt->name));
    tmp = (char *) (ct->name + sizeof(ct->name) - sizeof(void *));
    *(tmp - 1) = '\0';
    memcpy(tmp, &nt, sizeof(void *));

    ct->revision = nt->revision;
    ct->family = nt->family;
    ct->table = (char *) nt->table;
    ct->hooks = nt->hooks;
    ct->proto = nt->proto;
    ct->match = xtnu_match_run;
    ct->checkentry = xtnu_match_check;
    ct->destroy = xtnu_match_destroy;
    ct->matchsize = nt->matchsize;
    ct->me = nt->me;

    nt->__compat_match = ct;
    ret = xt_register_match(ct);
    if (ret != 0)
	kfree(ct);
    return ret;
}

EXPORT_SYMBOL_GPL(xtnu_register_match);

int xtnu_register_matches(struct xtnu_match *nt, unsigned int num)
{
    unsigned int i;
    int ret;

    for (i = 0; i < num; ++i) {
	ret = xtnu_register_match(&nt[i]);
	if (ret < 0) {
	    if (i > 0)
		xtnu_unregister_matches(nt, i);
	    return ret;
	}
    }
    return 0;
}

EXPORT_SYMBOL_GPL(xtnu_register_matches);

void xtnu_unregister_match(struct xtnu_match *nt)
{
    xt_unregister_match(nt->__compat_match);
    kfree(nt->__compat_match);
}

EXPORT_SYMBOL_GPL(xtnu_unregister_match);

void xtnu_unregister_matches(struct xtnu_match *nt, unsigned int num)
{
    unsigned int i;

    for (i = 0; i < num; ++i)
	xtnu_unregister_match(&nt[i]);
}

EXPORT_SYMBOL_GPL(xtnu_unregister_matches);
#endif

#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 18)
static unsigned int xtnu_target_run(struct sk_buff **pskb,
				    const struct net_device *in,
				    const struct net_device *out,
				    unsigned int hooknum,
				    const struct xt_target *ct,
				    const void *targinfo, void *userdata)
#elif LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 23)
static unsigned int xtnu_target_run(struct sk_buff **pskb,
				    const struct net_device *in,
				    const struct net_device *out,
				    unsigned int hooknum,
				    const struct xt_target *ct,
				    const void *targinfo)
#elif LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 27)
static unsigned int xtnu_target_run(struct sk_buff *skb,
				    const struct net_device *in,
				    const struct net_device *out,
				    unsigned int hooknum,
				    const struct xt_target *ct,
				    const void *targinfo)
#else
static unsigned int
xtnu_target_run(struct sk_buff *skb, const struct xt_target_param *par)
#endif
{
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 27)
    struct xtnu_target *nt = xtcompat_nutarget(ct);
    struct xt_target_param local_par = {
	.in = in,
	.out = out,
	.hooknum = hooknum,
	.target = ct,
	.targinfo = targinfo,
	.family = NFPROTO_UNSPEC,
    };
#else
    struct xtnu_target *nt = xtcompat_nutarget(par->target);
#endif

    if (nt != NULL && nt->target != NULL)
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 23)
	return nt->target(pskb, &local_par);
#elif LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 27)
	return nt->target(&skb, &local_par);
#else
	return nt->target(&skb, par);
#endif
    return XT_CONTINUE;
}

#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 18)
static int xtnu_target_check(const char *table, const void *entry,
			     const struct xt_target *ct, void *targinfo,
			     unsigned int targinfosize,
			     unsigned int hook_mask)
#elif LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 22)
static int xtnu_target_check(const char *table, const void *entry,
			     const struct xt_target *ct, void *targinfo,
			     unsigned int hook_mask)
#elif LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 27)
static bool xtnu_target_check(const char *table, const void *entry,
			      const struct xt_target *ct, void *targinfo,
			      unsigned int hook_mask)
#endif
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 27)
{
    struct xtnu_target *nt = xtcompat_nutarget(ct);
    struct xt_tgchk_param local_par = {
	.table = table,
	.entryinfo = entry,
	.target = ct,
	.targinfo = targinfo,
	.hook_mask = hook_mask,
	.family = NFPROTO_UNSPEC,
    };

    if (nt == NULL)
	return false;
    if (nt->checkentry == NULL)
	/* this is valid, just like if there was no function */
	return true;
    return nt->checkentry(&local_par);
}
#endif

#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 18)
static void xtnu_target_destroy(const struct xt_target *ct, void *targinfo,
				unsigned int targinfosize)
#elif LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 27)
static void xtnu_target_destroy(const struct xt_target *ct, void *targinfo)
#endif
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 27)
{
    struct xtnu_target *nt = xtcompat_nutarget(ct);
    struct xt_tgdtor_param local_par = {
	.target = ct,
	.targinfo = targinfo,
	.family = NFPROTO_UNSPEC,
    };

    if (nt != NULL && nt->destroy != NULL)
	nt->destroy(&local_par);
}
#endif

int xtnu_register_target(struct xtnu_target *nt)
{
    struct xt_target *ct;
    char *tmp;
    int ret;

    ct = kzalloc(sizeof(struct xt_target), GFP_KERNEL);
    if (ct == NULL)
	return -ENOMEM;

    tmp = (char *) ct->name;
    memcpy(tmp, nt->name, sizeof(nt->name));
    tmp = (char *) (ct->name + sizeof(ct->name) - sizeof(void *));
    *(tmp - 1) = '\0';
    memcpy(tmp, &nt, sizeof(void *));

    ct->revision = nt->revision;
    ct->family = nt->family;
    ct->table = (char *) nt->table;
    ct->hooks = nt->hooks;
    ct->proto = nt->proto;
    ct->target = xtnu_target_run;
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 27)
    ct->checkentry = xtnu_target_check;
    ct->destroy = xtnu_target_destroy;
#else
    ct->checkentry = nt->checkentry;
    ct->destroy = nt->destroy;
#endif
    ct->targetsize = nt->targetsize;
    ct->me = nt->me;

    nt->__compat_target = ct;
    ret = xt_register_target(ct);
    if (ret != 0)
	kfree(ct);
    return ret;
}

EXPORT_SYMBOL_GPL(xtnu_register_target);

int xtnu_register_targets(struct xtnu_target *nt, unsigned int num)
{
    unsigned int i;
    int ret;

    for (i = 0; i < num; ++i) {
	ret = xtnu_register_target(&nt[i]);
	if (ret < 0) {
	    if (i > 0)
		xtnu_unregister_targets(nt, i);
	    return ret;
	}
    }
    return 0;
}

EXPORT_SYMBOL_GPL(xtnu_register_targets);

void xtnu_unregister_target(struct xtnu_target *nt)
{
    xt_unregister_target(nt->__compat_target);
    kfree(nt->__compat_target);
}

EXPORT_SYMBOL_GPL(xtnu_unregister_target);

void xtnu_unregister_targets(struct xtnu_target *nt, unsigned int num)
{
    unsigned int i;

    for (i = 0; i < num; ++i)
	xtnu_unregister_target(&nt[i]);
}

EXPORT_SYMBOL_GPL(xtnu_unregister_targets);

struct xt_match *xtnu_request_find_match(unsigned int af, const char *name,
					 uint8_t revision)
{
    static const char *const xt_prefix[] = {
	[AF_UNSPEC] = "x",
	[AF_INET] = "ip",
	[AF_INET6] = "ip6",
#ifdef AF_ARP
	[AF_ARP] = "arp",
#elif defined(NF_ARP) && NF_ARP != AF_UNSPEC
	[NF_ARP] = "arp",
#endif
    };
    struct xt_match *match;

    match = try_then_request_module(xt_find_match(af, name, revision),
				    "%st_%s", xt_prefix[af], name);
    if (IS_ERR(match) || match == NULL)
	return NULL;

    return match;
}

EXPORT_SYMBOL_GPL(xtnu_request_find_match);

int xtnu_ip_route_me_harder(struct sk_buff **pskb, unsigned int addr_type)
{
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 17)
    /* Actually this one is valid up to 2.6.18.4, but changed in 2.6.18.5 */
    return ip_route_me_harder(pskb);
#elif LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 23)
    return ip_route_me_harder(pskb, addr_type);
#else
    return ip_route_me_harder(*pskb, addr_type);
#endif
}

EXPORT_SYMBOL_GPL(xtnu_ip_route_me_harder);

int xtnu_skb_make_writable(struct sk_buff **pskb, unsigned int len)
{
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 23)
    return skb_make_writable(pskb, len);
#else
    return skb_make_writable(*pskb, len);
#endif
}

EXPORT_SYMBOL_GPL(xtnu_skb_make_writable);

#if LINUX_VERSION_CODE == KERNEL_VERSION(2, 6, 24)
static int __xtnu_ip_local_out(struct sk_buff *skb)
{
    struct iphdr *iph = ip_hdr(skb);

    iph->tot_len = htons(skb->len);
    ip_send_check(iph);
    return nf_hook(PF_INET, NF_IP_LOCAL_OUT, skb, NULL,
		   skb->dst->dev, dst_output);
}

int xtnu_ip_local_out(struct sk_buff *skb)
{
    int err;

    err = __xtnu_ip_local_out(skb);
    if (likely(err == 1))
	err = dst_output(skb);

    return err;
}

EXPORT_SYMBOL_GPL(xtnu_ip_local_out);
#elif LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 23)
static int __xtnu_ip_local_out(struct sk_buff **pskb)
{
    struct iphdr *iph = ip_hdr(*pskb);

    iph->tot_len = htons((*pskb)->len);
    ip_send_check(iph);
    return nf_hook(PF_INET, NF_IP_LOCAL_OUT, pskb, NULL,
		   (*pskb)->dst->dev, dst_output);
}

int xtnu_ip_local_out(struct sk_buff *skb)
{
    int err;

    err = __xtnu_ip_local_out(&skb);
    if (likely(err == 1))
	err = dst_output(skb);

    return err;
}

EXPORT_SYMBOL_GPL(xtnu_ip_local_out);
#endif

#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 24)
int xtnu_ip_route_output_key(void *net, struct rtable **rp,
			     struct flowi *flp)
{
    return ip_route_output_flow(rp, flp, NULL, 0);
}

EXPORT_SYMBOL_GPL(xtnu_ip_route_output_key);

void xtnu_proto_csum_replace4(__sum16 * sum, struct sk_buff *skb,
			      __be32 from, __be32 to, bool pseudohdr)
{
    __be32 diff[] = { ~from, to };
    const void *dv = diff;	/* kludge for < v2.6.19-555-g72685fc */

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 19)
    if (skb->ip_summed != CHECKSUM_PARTIAL) {
	*sum = csum_fold(csum_partial(dv, sizeof(diff),
				      ~csum_unfold(*sum)));
	if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
	    skb->csum = ~csum_partial(dv, sizeof(diff), ~skb->csum);
    } else if (pseudohdr) {
	*sum = ~csum_fold(csum_partial(dv, sizeof(diff),
				       csum_unfold(*sum)));
    }
#else
    *sum = csum_fold(csum_partial(dv, sizeof(diff), ~csum_unfold(*sum)));
#endif
}

EXPORT_SYMBOL_GPL(xtnu_proto_csum_replace4);
#endif

#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 19)
int xtnu_neigh_hh_output(struct hh_cache *hh, struct sk_buff *skb)
{
    unsigned int hh_alen;

    read_lock_bh(&hh->hh_lock);
    hh_alen = HH_DATA_ALIGN(hh->hh_len);
    memcpy(skb->data - hh_alen, hh->hh_data, hh_alen);
    read_unlock_bh(&hh->hh_lock);
    skb_push(skb, hh->hh_len);
    return hh->hh_output(skb);
}

EXPORT_SYMBOL_GPL(xtnu_neigh_hh_output);

static inline __wsum xtnu_csum_unfold(__sum16 n)
{
    return (__force __wsum) n;
}

void xtnu_csum_replace4(__sum16 * sum, __be32 from, __be32 to)
{
    __be32 diff[] = { ~from, to };
    *sum = csum_fold(csum_partial((char *) diff, sizeof(diff),
				  ~xtnu_csum_unfold(*sum)));
}

void xtnu_csum_replace2(__sum16 * sum, __be16 from, __be16 to)
{
    xtnu_csum_replace4(sum, (__force __be32) from, (__force __be32) to);
}

EXPORT_SYMBOL_GPL(xtnu_csum_replace2);
#endif

#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 17)
int xtnu_skb_linearize(struct sk_buff *skb)
{
    return skb_linearize(skb, GFP_ATOMIC);
}

EXPORT_SYMBOL_GPL(xtnu_skb_linearize);
#endif

MODULE_LICENSE("GPL");
